Method of separating nickel and cobalt compounds from each other



May 28, 1957 VOOS METHOD OF SEPARATING NICKEL. AND COBALT COMPOUNDS FROM EACH OTHER Filed July 13,

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United States Patent C METHOD F SEPARATING NICKEL AND COBALT COMPOUNDS FROM EACH OTHER Walter Voos, Gampel, Switzerland, assigner to Lonza Electric and Chemical Works Ltd., Basel, Switzerland Application July 13, 1955, Serial No. 521,837

Claims priority, application Switzerland July 19, 1954 6 Claims. (Cl. 23-183) The present invention relates to a method of separating nickel and cobalt compounds from each other, and more particularly to the separation of nickel and cobalt which are in the form of divalent and trivalent mixed hydroxides thereof from each other.

Mixtures of divalent and trivalent nickel and cobalt hydroxides are obtained in the metallurgical processing of raw ore in dry, wet or electrochemical manners, or also in any other treatment. None of the known processes have been able to achieve satisfactory separation of the nickel hydroxides from the cobalt hydroxides particularly in cases where the ratio of nickel to cobalt in the mixed hydroxide varied.

It is therefore a primary object of the present invention to provide a simple and easily controllable method` for the separation of nickel and cobalt, particularly in the form of the hydroxides, from each other.

It is another object of the present invention to provide a method of separating nickel and cobalt compounds from each other, which method may be employed no matter what the ratio of nickel to cobalt in the mixture.

It is still another object of the present invention to provide a method of achieving substantially complete separation of nickel and cobalt compounds from each other.

It is a further object of the present invention to provide a particularly advantageous method of oxidizing divalent nickel and :cobalt hydroxides to trivalent nickel and cobalt hydroxides and to the separation of the produced trivalent nickel and cobalt hydroxides from each other.

Other objects and advantages of the present invention will be apparent from a further reading of the specification and of the appended claims. y

With the above objects in view, the present invention mainly consists in a method of separating nickel and cobalt compounds from each other, comprising the Steps of oxidizing a mixture of nickel and cobalt hydroxides, at least a portion of which are in divalent form, so as to form a mixture of trivalent nickel hydroxide and trivalent cobalt hydroxide, and extracting the thus-formed mixture of trivalent nickel and cobalt hydroxides with an aqueous chlorine-containing liquor in an amount suiicient to cause dissolution of substantially all of the trivalent nickel hydroxide, the trivalent cobalt hydroxide remaining undissolved, thereby separating the nickel hydroxide from the cobalt hydroxide.

Due to the fact that mixtures of nickel and cobalt hy- -droxides which are obtained in industry from metallurgical treatments are almost always in the form of mixtures of divalent and trivalent nickel and cobalt hydroxides, it is necessary in accordance with the present invention to iirst oxidize such mixtures so as to convert all of the hydroxides to the trivalent form before the extracting step in order to prevent the loss of any of the nickel or cobalt.

In accordance with the present invention, the oxidation is preferably carried out in a liquid medium in which the mixtureof divalent ,and trivalent-nickel landcobalt hydroxides is insoluble. Most preferably, the liquid ice medium is an aqueous medium and in such case the amount of the aqueous medium with reference to the amount of the mixed hydroxides should be such that a slurry or pasty mixture is formed. The oxidation is most preferably carried out by means of a chlorine-containing solution or a solution which gives up chlorine, e. g., by an aqueous solution containing chlorine, a soluble chlorate or hypochlorite. By the oxidation of the mixed hydroxides in the form of a slurry, that is, in the presence of a small amount of liquid, for example between 10 and 60%, and most preferably between 30 and 40% of water as against the amount of the mixed hydroxides, so that the mixture of the water and the mixed hydroxides is in the form of a slurry or a foam, loss of substance by dissolution is greatly avoided.

In addition to the above mentioned oxidation agents, such as chlorine, chlorates and hypochlorites, any other suitable oxidation agent may be utilized provided no undesirable residue from the oxidation remains. The oxidation is preferably carried out at room temperature, although higher temperatures may be utilized within practical limits; for example, inthe case of utilizing chlorine as the oxidizing agent a temperature of C. should not be exceeded in order to prevent the chlorine from volatilizing. Temperatures of 40-50 C. are most suitable.

After oxidation in a liquid medium in which the hydroxides form a slurry, the oxidized hydroxides, e. g., trivalent nickel and cobalt hydroxides, are separated from the liquid medium by filtration or, preferably, centrifugation. The mixture of trivalent nickel and cobalt hydroxides are then subject to extraction by means of a large amount of a chlorine-containing aqueoussolution whereby substantially all of the trivalent nickel hydroxide goes into solution while substantially all of the trivalent cobalt` hydroxide remains undissolved. The nickel hydroxide and the cobalt hydroxide may then be recovered separately by any suitable means. The extracting agent must be an aqueous solution of chlorine. Although the other halogens can be used instead of chlorine, they are so expensive as to be industrially impractical. The aqueous solution is preferably saturated with chlorine and, in order to increase the amount of chlorine which the solution may contain and thereby to increase the dissolving ability for trivalent nickel hydroxide of the solution, the aqueousl solution should also contain a carrier salt which has the property of permitting the aqueous solution to Ihold more chlorine and simultaneously aid in the extraction of the trivalent nickel hydroxide.

Such carrier salt is preferably the chloride of a metal, the hydroxide of which is water soluble. For example, sodium chloride, calcium chloride are suitable for this purpose. Sodium chloride is, of course, most preferred for reasons of ready availability and economy.

The aqueous extracting solution preferably contains between 50 and 500g. per liter of sodium chloride, most preferably between 200 and 300 g. per liter. The solution is further preferably saturated with chlorine.

The amount of the aqueous chlorine-containing solu-' tion can be varied within rather Wide limits. Generally at least 500 liters of the aqueous solution per 30 kg. of the hydroxides is needed in order to assure dissolution of all of the trivalent nickel hydroxide, although the amount of course depends upon the amount of trivalent nickel hydroxide in the mixture of trivalent nickel and cobalt hydroxides. There is actually no maximum amount of solution which may be used, although as a practical matter, in order to avoid the necessity of extremely large apparatus, the amount of solution should not exceed 3,000 liters per kg. of the hydroxides. Most preferably, between 1500 and 2000 liters per 180 kg. is

- utilized.-

The extraction is preferably carried out at a temperature between 50-l00 C., rand most preferably between 90-95 C.

As stated previously, in accordance with the present invention the extraction results in dissolving of the, trivalent nickel hydroxide in the chlorine-containing so- 1ution,'while the trivalent cobalt hydroxide remains undissolved. The leaching or extraction of the mixed hydroxides can be so carried out until the regular control of thebottom residue, depending upon the requirements of the operation, shows only traces of the nickel, or until the leached product is free of nickel.

The separation o f the nickel from the cobalt can be carried out to a degree of 100% so that in the nickel solution no cobalt is'present as shown by means of a-nit'roso--naphthol, while in the cobalt residue no nickel is present as can be shown by means of dimethylglyoxime. Y

- The oxidation is preferably carried out in a vessel provided with a stirrer in which the mixed hydroxide is stirred with the small amount of oxidizing solution in the form of a slurry until lthe desired conversion of thenickel and cobalt into the trivalent form is achieved.

The leaching or extracting of the trivalent nickel hydroxide from the trivalent cobalt hydroxide is carried out in suspensions in larger amounts of liquid and can also be carried out in vessels provided with stirrers, although to improve the extraction it is also possible to operate in an autoclave under pressure.

The extracted most pure nickel solution or the remainingmost pure cobaltic hydroxide can by any suitable 'means be worked up into pure salts, oxides, catalysts, reducing metals, hard metals, electrolyte metals, or metal powders, while the aqueous chlorine-containing solution which would generally also contain a carrier salt, such as the sodium chloride, can be recovered and/or recirculated for further extraction.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, willbe best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which the ow sheet of the drawing illustrates diagrammatically the separation of nickel and cobalt from each other in accordance with the present invention.

The following examples are given to further illustrate the method of the present invention, the scope of the invention not, however, being limited to the specific details of the examples:

Example 1 180 kg. of mixed hydroxide of cobalt and nickel including divalent and trivalent hydroxides of each (the ratio of cobalt to nickel being :1) are introduced into a container and 90 kg. of tap water, e. g., an amount sufcient to form only a slurry, is added. The thus obtained slurryis subjected to an oxidizing treatment in which, while stirring atvroom temperature, chlorine gas in fine subdivision is introduced into the slurry until the metal hydroxide mixture has a black color through and through indicating that both the nickel and the cobalt are in trivalentform.

The oxidized slurry is then introduced into a centrifuge and there the solid particles are separated from the liquid by centrifugation. The spent liquor can serve for the treatment of fresh raw material.

3,000 liters of .tap water containing about 300 'g./l. of NaCl, which serves as a carrier salt for chlorine gas and ,also to `aid in the extraction, is'heated to a temperature of ,4i-50 C. in aV 31/2 m3 vessel. Chlorine gas is then introduced into the solution until thesolution has an intense yellow color and shows an acid re action. The temperature is then increased to 9D-95 C.

The extraction is then carried out as follows: The mixture of trivalent cobalt and nickel obtained by the oxidation of the 180 kg. of the mixed hydroxides, which trivalent compounds are in the form of a 180 kg. cake, are added to the solution slowly while stirring. After the introduction is completed the leaching is continued for 30 minutes at 90-95 C. and thereafter the aqueous solution content of chlorine gas is renewed. Alternate periods of 30 minutes extraction and renewed addition of chlorine gas are continued until the desired purity of the cobalt hydroxide is achieved. The separation of the nickel and mother liquor or the later precipitated wash water from the liquor residue from the cobaltic hydroxide is carried out by centrifugation. The nickel containing liquor and the cobaltic hydroxide can be further worked up to the desired end product while the wash water can be utilized .for treatment of additionalA raw material.

Example 2 200 kg. of a mixture of cobalt and nickel divalent and trivalent hydroxides (ratio of cobalt to nickel being 1:1) are introduced into a container with only so much tap water as to form a slurry, i. e., with 60 kg. of tapwater. The thus obtained slurry is subjected to an oxidation treatment wherein under stirring at room temperature chlorine gas is introduced in finest subdivision until the metal hydroxide mixture has a black color through and through indicating the trivalent form of the metals.

This mass is introduced into centrifuge and there subjected to centrifugation. The spent liquor can servefor the treatment of fresh raw material.

3000 liters of tap water containing about 240 g./l.` of NaCl, which serves as a carrier salt for chlorine gas and to improve the extraction, is heated in a 31/2 rn.3 vesselv to a temperature of 60-65 C. Chlorine gas is then in-.

troduced until the solution has an intense yellow color and gives an acid reaction. The temperature is then raised to between -90" C.

The extraction is then carried out by the addition of the mixed trivalent hydroxides to the solution slowly while stirring. After introduction of all of the hydroxides the leaching is continued for 20 minutes at 85-90 C. and thereupon the solution is again saturated with chlorine gas. AlternateV SO-minute extractions and renewed additions of chlorine gas are continued until the desired purity of the cobaltic hydroxide has been obtained. The separation of the nickel mother liquor or the later precipitated wash water from the leaching residue from the cobaltic hydroxide is accomplished by means of a centrifuge.

An important advantage of the method of the presentinvention is that it can be carried out with any ratio of.

cobalt to nickel-or nickel to cobalt without any necessary important changes in the method of proceeding. Any

additional important advantage of the method of the present invention is that it can be carried out without the necessity of carefully controlling the pH and maintaining the pH within narrow limits. Therefore, the method of the present invention permits much easier proceeding than known methods.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can,

by applying current knowledge, readilyV adapt it for various l applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention, Aand therefore such adaptations should and areintended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured-by Letters Batent is:

v 1. ,A method of, completelyl separatingtnickel 1 andA con..

balt compounds from each other, comprising the steps of subjecting a mixture of nickel and cobalt hydroxides at least a portion of which are in divalent form to oxidation in a suiciently small amout of an aqueous medium to prevent dissolution of trivalent nickel and cobalt hydroxides so that said aqueous medium and said mixture of nickel and cobalt hydroxides is in the form of a pasty mass, thereby forming a mixture of trivalent nickel hydroxide and ltrivalent cobalt hydroxide distributed in said aqueous medium; separating said trivalent nickel and cobalt hydroxides from said aqueous medium; and extracting the thus formed mixture of trivalent nickel and cobalt hydroxides with an aqueous chlorine-containing liquor in an amount suflicient to cause dissolution of all of said Itrivalent nickel hydroxide, said trivalent cobalt hydroxide remaining undissolved, thereby separating said nickel hydroxide from said cobalt hydroxide.

2. A method of completely separating nickel and cobalt compounds from each other, comprising the steps of subjecting a mixture of nickel and cobalt hydroxides at least a portion of which are in divalent form to oxidation in an aqueous medium, said aqueous medium being in an amount of -60% by weight of said mixture of nickel and cobalt hydroxides so that said aqueous medium and said mixture of nickel and coalt hydroxides is in the form of a pasty mass, thereby forming a mixture of 'trivalent nickel hydroxide and trivalent cobalt hydroxide distributed in said aqueous medium; separating said trivalent nickel and cobalt hydroxides from said aqueous medium; and extracting the thus formed mixture of trivalent nickel and cobalt hydroxides with an aqueous chlorine-containing liquor in an amount suflicient to cause dissolution of all of said trivalent nickel hydroxide, said trivalent cobalt hydroxide remaining undissolved, thereby separating said nickel hydroxide from said cobalt hydroxide.

3. A method of completely separating nickel and cobalt compounds from each other, comprising the steps of subjecting a mixture of nickel and cobalt hydroxides at least a portion of which are in divalent form to oxidation in an aqueous medium, said aqueous medium being in an amount of 10-60% by weight of said mixture of nickel and cobalt hydroxides so that said `aqueous medium and said mixture of nickel and cobalt hydroxides is in the form of a pasty mass, thereby forming a mixture of trivalent nickel hydroxide and trivalent cobalt hydroxide distributed in said aqueous medium; separating said trivalent nickel and cobalt hydroxides from said aqueous medium; and extracting the thus formed mixture of trivalent nickel and cobalt hydroxides with an aqueous chlorine-containing liquor containing in solution the chloride of a cation the hydroxide of which is water-soluble in an amount sufficient to cause dissolution of all of said trivalent nickel hydroxide, said trivalent cobalt hydroxide remaining undissolved, thereby separating said nickel hydroxide from said cobalt hydroxide.

4. A method of completely separating nickel and cobalt compounds from each other, comprising the steps of subjecting a mixture of nickel and cobalt hydroxides at least a portion of which are in divalent form to oxidation by means of chlorine in an aqueous medium, said aqueous medium'being in an amount of 10-60% by Weight of said mixture of nickel and cobalt hydroxides so that said aqueous medium and said mixture of nickel and cobalt hydroxides is in the form of a pasty mass, thereby forming a mixture of trivalent nickel hydroxide and trivalent cobalt hydroxide distributed in said aqueous medium; separating said trivalent nickel and cobalt hydroxides from said aqueous medium; and extracting the thus 6 formed mixture of trivalent nickel and cobalt hydroxides with an aqueous solution ot sodium chloride containing y also chlorinein an amount sulcient to cause dissolution of all of said trivalent nickel hydroxide, said trivalent cobalt hydroxide remaining undissolved, thereby separating said nickel hydroxide from said cobalt hydroxide.

5. A method of completely separating nickel and cobalt compounds from each other, comprising the steps of subjecting a mixture of nickel and cobalt hydroxides at least a portion of which are in divalent form to oxidation in an aqueous medium, said aqueous medium being in an amount of lO-60% by weight of said mixture of nickel and cobalt hydroxides so that said aqueous medium and said mixture of nickel and cobalt hydroxides is in the form of a pasty mass, thereby forming a mixture of trivalent nickel hydroxide and trivalent cobalt hydroxide; separating said trivalent nickel and cobalt hydroxides from said aqueous medium; and extracting the thus formed mixture of trivalent nickel and cobalt hydroxides with an aqueous solution of sodium chloride saturated with chlorine and containing between 50 and 500 g. of sodium chloride per liter and being in an amount of between 500 and'3,000 liters of solutions per 30 up to 180 kg. of said trivalent nickel and cobalt hydroxides so as to cause dissolution of all of said trivalent nickel hydroxide, said trivalent cobalt hydroxide remaining undissolved, thereby separating ysaid nickel hydroxide from said cobalt hydroxide.

6. A method of completely separating nickel and cobalt compounds from each other, ycomprising the `steps of subjecting a mixture of nickel and cobalt hydroxides at least a portion of which are in divalent form to oxidation by means of chlorine in an aqueous medium, said aqueous medium being in an amount of 3040% by Weight of said mixture of nickel and cobalt hydroxides so that said aqueous medium and said mixture of nickel and cobalt hydroxides is in the form of a pasty mass, thereby forming a mixture of trivalent nickel hydroxide and trivalent cobalt hydroxide distributed in said aqueous medium; separating said trivalent nickel and cobalt hydroxides from said aqueous medium; and extracting the thus formed mixture of trivalent nickel and cobalt hydroxides at a temperature of 50-100 C. with ran aqueous solution of sodium chloride saturated with chlorine and containing between 50 and 500 g. of sodium chloride per liter and being in an amount of between 500 and 3,000 liters of solutions per 30 up to 180 kg. of said trivalent nickel and cobalt hydroxides so as to cause dissolution of all of said trivalent nickel hydroxide, said trivalent cobalt hydroxide remaining undissolved, thereby `separating said nickel hydroxide from said cobalt hydroxide.

References Cited in the le of this patent UNITED STATES PATENTS 1,596,253 Harshaw et al. Aug. 17, 1926 2,488,561 Schaal Nov. 22, 1949 2,726,144 Wallis et al. Dec. 6, 1955 FOREIGN PATENTS 570,231 Great Britain June 28, 1945 OTHER REFERENCES J. W. Mellors A Comprehensive Treatise on Inorganic and Theoretical Chemistry, vol. 14, pages 570 and 572, vol. 15, pages 385 and 386.

Roscoe and Schorlemmer: Treatise on Chemistry, vol. 2, 1907 ed., page 1278. McMillan and Co. Ltd., London. 

1. A METHOD OF COMPLETELY SEPARATING NICKEL AND COBALT COMPOUNDS FROM EACH OTHER, COMPRISING THE STEPS OF SUBJECTING A MIXTURE OF NICKEL AND COBALT HYDROXIDES AT LEAST A PORTION OF WHICH ARE IN DIVALENT FORM TO OXIDATION IN A SUFFICIENTLY SMALL AMOUNT OF AN AQUEOUS MEDIUM TO PREVENT DISSOLUTION OF TRIVALENT NICKEL AND COBALT HYDROXIDES TO THAT SAID AQUEOUS MEDIUM AND SAID MIXTURE OF NICKEL AND COBALT HYDROXIDES IS IN TEH FORM OF A PASTY MASS, THEREBY FORMING A MIXTURE OF TRIVALENT NICKEL HYDROXIDE AND TRIVALENT COBALT HYDROXIDE DISTRIBUTED IN SAID AQUEOUS MEDIUM; SEPARATING SAID TRIVALENT NICKEL AND COBALT HYDROXIDES FROM SAID AQUEOUS MEDIUM; AND EXTRACTING THE THUS MIXTURE OF TRIVALENT NICKEL AND COBALT HYDROXIDES WITH AN AQUEOUS CHLORINE-CONTAINING LIQUOR IN AN AMOUNT SUFFICIENT TO CAUSE DISSOLUTION OF ALL 